STUDIES ON THE CYTOTOXIC CONSTITUENTS OF CYNANCHUM AURICULATUM ROYLE EX WIGHT

AIM　To isolate and elucidate the chemical structures of two C-21 steroidal glycosides possessing cytotoxic activity from the root of Cynanchum auriculatum Royle ex Wight (Asclepiadaceae). METHODS　The glycosides were isolated and purified by column chromatography on silica gel and HPLC. The molecular structures were determined on the basis of chemical evidence and extensive spectral analysis(UV, IR, ¹HNMR, ¹³CNMR, DEPT, HR-FAB-MS, FAB-MS, HMQC and HMBC). RESULTS　Two C-21 steroidal glycosides, named cynanauriculosides A and B, were obtained and their structures were elucidated as caudatin 3-O-β-D-glucopyranosyl-(1→4)-β-D-cymaropynanosyl-(1→4)-β-D-oleandropyranosyl-(1→4)-β-D-cymaropynanoside and caudatin 3-O-β-D-glucopyranosyl-(1→4)-β-D-oleandropyranosyl-(1→4)-β-D-digitoxopyranosyl-(1→4)-β-D-cymaropynanoside respectively. CONCLUSION　Cynanauriculosides A and B are new compounds.